Method of producing a plant growth substrate

ABSTRACT

The present invention relates to a method of producing a coherent growth substrate product formed of man-made vitreous fibres (MMVF), comprising the steps of (vi) providing MMVF; (vii) providing an uncured binder composition; (viii) providing a superabsorbent polymer; (ix) forming a mixture of the MMVF, the uncured binder composition and the superabsorbent polymer; (x) curing the uncured binder composition in the mixture to form the coherent growth substrate product; wherein the uncured binder composition comprises at least one hydrocolloid.

FIELD OF THE INVENTION

The present invention relates to a method of producing a coherent growth substrate, a coherent growth substrate product, a method of propagating seeds or seedlings, a method of growing plants and use of a coherent growth substrate.

BACKGROUND OF THE INVENTION

It has been known for many years to grow plants in coherent growth substrates formed from man-made vitreous fibres (MMVF). MMVF products for this purpose, which are provided as a coherent plug, block or slab, generally include a binder, usually an organic binder, in order to provide structural integrity to the product. Such binders are conventionally associated with extensive curing times and high curing temperatures, and specific curing equipment is needed for curing the binder composition. The curing equipment is conventionally an oven operating at a temperature of 150° C. to 300° C., often 200° C. to 275° C.

At the same time, it is desirable for coherent plant growth substrates to have additives incorporated therein. In particular, additives which improve re-saturation properties; water distribution properties; water retention; initial wetting; seed germination, rooting-in and plant growth are commonly used in plant growth substrates. Often these additives are negatively impacted by high temperatures. For example, the additives may start to degrade, decompose or be destroyed by temperatures of 50° C. or more, such as 100° C. or more or 200° C. or more and are not able to provide their desired function once decomposed.

Particularly desirable additives are superabsorbent polymers. Such polymers can absorb fluid and retain it under pressure without dissolution in the fluid being absorbed. However, superabsorbent polymers may start to degrade or are destroyed by temperatures of 50° C. or more, such as 100° C. or more or 200° C.

It is therefore necessary to add these additives after the binder composition has been cured in a conventional curing oven, if a binder composition is to be used.

US 2014/0130410 discloses a method for including superabsorbent polymers in a MMVF plant growth substrate. This process involves needling the superabsorbent polymer into the substrate in order to avoid the use of a binder composition, and its associated high curing temperature which would degrade the superabsorbent polymer. However, this process requires the use of complex equipment and does not allow for the presence of any binder, which negatively affects the structural integrity of the substrate.

It would therefore be desirable to produce a binder composition which cures at 5-95° C., 5 to 80° C., such as 10 to 60° C., such as 20 to 40° C., and therefore allows addition of temperature-sensitive additives, such as superabsorbent polymers, before curing of the binder composition occurs, and which does not result in the additives degrading or decomposing such that they cannot perform their desired function.

Furthermore, known binder compositions, in addition to requiring high curing temperatures, typically include phenol-formaldehyde resins, as these can be economically produced. Examples of documents which disclose the use of formaldehyde-containing binders include WO2009/090053, WO2008009467, WO2008/009462, WO2008/009461, WO2008/009460 and WO2008/009465. However, these binders suffer from the disadvantage that they contain formaldehyde. There have been suggestions that formaldehyde compounds can be damaging to health and are therefore environmentally undesirable; this has been reflected in legislation directed to lowering or eliminating formaldehyde emissions. Furthermore, formaldehyde is known to have negative effects in terms of phytotoxicity.

Other types of binder than the standard phenol urea formaldehyde type have been disclosed for use in MMVF growth substrates

Examples of non-phenol-formaldehyde binders include those described in WO2017/114723 and WO2017/114724. However, these binders require a high curing temperature, such as at least 200° C.

WO2012/028650 discloses a mineral fibre product comprising MMVF bonded with a cured binder composition, wherein the binder composition prior to curing comprises (i) a sugar component, (ii) a reaction product of a polycarboxylic acid component and an alkanolamine component. The binder composition of WO2012/028650 requires high curing temperatures such as of 200° C. to 300° C. In addition, the starting materials used in the production of these binders are rather expensive chemicals. Therefore, there is an on-going need to provide formaldehyde-free binders which have low curing temperatures and are economically produced.

A further effect in connection with previously known binder compositions for plant growth substrates is that at least the majority of the starting materials used for the production of these binders stems from fossil fuels. There is an on-going trend for consumers to prefer products that are fully or at least partly produced from renewable materials and there is therefore a need to provide binders for plant growth substrates which are at least partly produced from renewable materials. Preferably the binder is produced from non-toxic materials.

Binder compositions based on renewable materials have been proposed before. However, there are still some disadvantages of MMVF products prepared with these binders in terms of strength when compared with MMVF products prepared with phenol-formaldehyde resins.

The reference EP 2424886 B1 (Dynea OY) describes a composite material comprising a crosslinkable resin of a proteinous material. In a typical embodiment, the composite material is a cast mould comprising an inorganic filler, like e.g. sand, and/or wood, and a proteinous material as well as enzymes suitable for crosslinking the proteinous material. A mineral wool product is not described in EP 2424886 B1.

The reference C. Peña, K. de la Caba, A. Eceiza, R. Ruseckaite, I. Mondragon in Biores. Technol. 2010, 101, 6836-6842 is concerned with the replacement of non-biodegradable plastic films by renewable raw materials from plants and wastes of meat industry. In this connection, this reference describes the use of hydrolysable chestnut-tree tannin for modification of a gelatin in order to form films. The reference does not describe binders, in particular not binders for mineral wool.

A further effect in connection with previously known binder compositions is that they involve components which are corrosive and/or harmful. This requires protective measures for the machinery involved in the production of growth substrates to prevent corrosion and also requires safety measures for the persons handling this machinery. This leads to increased costs and health issues.

It would be desirable to have a method of producing a growth substrate which allows for temperature-sensitive additives, such as superabsorbent polymers, to be incorporated before a binder composition is cured. Temperature-sensitive means additives which starts to degrade, decompose or be destroyed when exposed to temperatures of 50° C. or more, such as 100° C. or more or 200° C., such as between 50 to 300° C., such as 80° C. to 230° C. or 100° C. to 200° C. It would therefore be desirable to produce a binder composition which does not require high temperatures for curing. It would be desirable for the binder composition to have a curing temperature which does not degrade, decompose or destroy temperature-sensitive additives, such as superabsorbent polymers. In addition, it would be desirable for this binder composition to be formaldehyde-free. It would also be desirable for the binder composition to be derived mostly from renewable materials. It would also be desirable for the binder composition to be economical to produce. It would be desirable for the binder composition to be free from components which are corrosive and/or harmful.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there is provided a method of producing a coherent growth substrate product formed of man-made vitreous fibres (MMVF), comprising the steps of:

-   -   (i) providing MMVF;     -   (ii) providing an uncured binder composition;     -   (iii) providing a superabsorbent polymer;     -   (iv) forming a mixture of the MMVF, the uncured binder         composition and the superabsorbent polymer;     -   (v) curing the uncured binder composition in the mixture to form         the coherent growth substrate product;

wherein the uncured binder composition comprises at least one hydrocolloid.

In accordance with a second aspect of the present invention, there is provided coherent growth substrate product comprising;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition; and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid.

In accordance with a third aspect of the present invention, there is provided use of a coherent growth substrate product as a substrate for growing plants or for propagating seeds;

wherein the coherent growth substrate product comprises;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition; and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid.

In accordance with a fourth aspect of the present invention, there is provided a method of growing plants in a coherent growth substrate product, the method comprising:

-   -   (i) providing at least one growth substrate product;     -   (ii) positioning one or more plants for growth in the growth         substrate product; and     -   (iii) irrigating the growth substrate product;

wherein the coherent growth substrate product comprises;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition;     -   and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid.

In accordance with a fifth aspect of the present invention, there is provided a method of propagating seeds in a coherent growth substrate product, the method comprising:

-   -   (i) providing at least one growth substrate product     -   (ii) positioning one or more seeds in the growth substrate         product,     -   (iii) irrigating the growth substrate product; and     -   (iv) allowing germination and growth of the seed to form a         seedling;

wherein the coherent growth substrate product comprises;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition;     -   and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid.

The present inventors have surprisingly found that it is possible to produce a binder composition, as described above, which has a low curing temperature. This allows additives which would normally start to degrade, decompose or be destroyed by high temperatures to be included in a growth substrate, along with a binder composition, and in particular, before the binder composition is cured.

The inventors also surprisingly discovered that a binder composition with the above-described advantages can be produced from renewable materials to a large degree. In addition, the binder composition is formaldehyde-free, economical to produce and does not contain components which are corrosive and/or harmful.

DETAILED DESCRIPTION OF INVENTION

Method of Producing Growth Substrate

The present invention provides a method of producing a coherent growth substrate product formed of man-made vitreous fibres (MMVF), comprising the steps of:

-   -   (i) providing MMVF;     -   (ii) providing an uncured binder composition;     -   (iii) providing a superabsorbent polymer;     -   (iv) forming a mixture of the MMVF, the uncured binder         composition and the superabsorbent polymer;     -   (v) curing the uncured binder composition in the mixture to form         the coherent growth substrate product;

wherein the uncured binder composition comprises at least one hydrocolloid and preferably at least one fatty acid ester of glycerol;

In the present invention, man-made vitreous fibres (MMVF) are provided. The MMVF may be made by any of the methods known to those skilled in the art for production of MMVF growth substrate products. In general, a mineral charge is provided, which is melted in a furnace to form a mineral melt. The melt is then formed into fibres by means of rotational fiberisation.

The melt may be formed into fibres by external centrifuging e.g. using a cascade spinner, to form a cloud of fibres. Alternatively, the melt may be formed into fibres by internal centrifugal fiberisation e.g. using a spinning cup, to form a cloud of fibres.

Typically, these fibres are then collected to form a primary fleece or web, the primary fleece or web is then cross-lapped to form a secondary fleece or web. The secondary fleece or web is then cured and formed into a growth substrate.

The MMVF can be of the conventional type used for formation of known MMVF growth substrates. It can be glass wool or slag wool but is usually stone wool. Stone wool generally has a content of iron oxide at least 3% and content of alkaline earth metals (calcium oxide and magnesium oxide) from 10 to 40%, along with the other usual oxide constituents of mineral wool. These may include silica; alumina; alkali metals (sodium oxide and potassium oxide), titania and other minor oxides. In general it can be any of the types of man-made vitreous fibre which are conventionally known for production of growth substrates.

The geometric mean fibre diameter is often in the range of 1.5 to 10 microns, in particular 2 to 8 microns, preferably 3 to 6 microns as conventional.

In the present invention, the uncured binder composition may be added to the MMVF at the fiberisation stage. The fiberisation stage is the stage at which the fibres are formed. This involves adding the uncured binder composition to the fibres as they form i.e. to the clouds of fibres as they form. These methods are well known in the art. Preferably, the uncured binder composition is sprayed onto the fibres as they form i.e. onto the clouds of forming fibres. The uncured binder composition may be added in solid or liquid form. Preferably the uncured binder composition is in liquid form, most preferably in aqueous form.

Alternatively, the uncured binder composition may be added to the fibres after they have formed. The uncured binder composition may be added to the fibres that are formed from either internal or external centrifugal fiberisation. The uncured binder composition may be added in solid or liquid form, preferably in liquid form, most preferably in aqueous form.

The superabsorbent polymer may be added after the fibres are formed. The superabsorbent polymer may be added to the fibres that are formed from either internal or external centrifugal fiberisation. The superabsorbent polymer is preferably added to a primary fleece or web. Preferably the superabsorbent polymer is added as particles.

If the uncured binder composition and the superabsorbent polymer are added after fiberisation, such as to the primary web or fleece then they can be added simultaneously or consecutively. For example, the uncured binder composition may be added first to the formed fibres, and then the superabsorbent polymer added subsequently. Alternatively, the uncured binder composition and superabsorbent polymer may be combined into a mixture, and said mixture is then added to the formed fibres. An advantage of adding the uncured binder composition and the superabsorbent polymer to the primary web or fleece is that the step is carried out further away from the spinner. As a result this step is carried out at a lower temperature than the fibres are formed at.

Alternatively, the superabsorbent polymer may be added first to the formed fibres and the uncured binder composition added subsequently.

The uncured binder composition may be added to the fibres as they form i.e to the clouds of fibres as they form, and the superabsorbent polymer is subsequently added to the formed fibres.

Preferably, the uncured binder composition and the superabsorbent polymer are added at the same stage, as this simplifies the overall process of producing the growth substrate, by avoiding an additional step in manufacturing. Most preferably, the uncured binder composition and the superabsorbent polymer are both added after fiberisation, such as to the primary web or fleece as it simplifies the process of producing the growth substrate by avoiding an additional step in manufacturing.

Once the uncured binder composition and the superabsorbent polymer are added to the fibres, in any of the methods outlined above, the binder composition is then cured to form the coherent growth substrate.

Curing

The binder composition is cured by a chemical and/or physical reaction of the binder composition components.

In one embodiment, the curing takes place in a curing device. In one embodiment the curing is carried out at temperatures from 5 to 95° C., such as 5 to 80° C., such as 5 to 60° C., such as 8 to 50° C., such as 10 to 40° C.

In one embodiment the curing takes place in a conventional curing oven for mineral wool production operating at a temperature of from 5 to 95° C., such as 5 to 80° C., such as 10 to 60° C., such as 20 to 40° C.

The curing process may commence immediately after application of the binder to the fibres. The curing is defined as a process whereby the binder composition undergoes a physical and/or chemical reaction which in case of a chemical reaction usually increases the molecular weight of the compounds in the binder composition and thereby increases the viscosity of the binder composition, usually until the binder composition reaches a solid state.

In one embodiment the curing process comprises cross-linking and/or water inclusion as crystal water.

In one embodiment the cured binder contains crystal water that may decrease in content and raise in content depending on the prevailing conditions of temperature, pressure and humidity.

In one embodiment the curing process comprises a drying process.

In one embodiment the curing process comprises drying by pressure. The pressure may be applied by blowing air or gas through/over the mixture of mineral fibres and binder composition. The blowing process may be accompanied by heating or cooling or it may be at ambient temperature.

In one embodiment the curing is performed in oxygen-depleted surroundings. Without wanting to be bound by any particular theory, the applicant believes that performing the curing in an oxygen-depleted surrounding is particularly beneficial when the binder composition includes an enzyme because it increases the stability of the enzyme component in some embodiments, in particular of the transglutaminase enzyme, and thereby improves the crosslinking efficiency. In one embodiment, the curing process is therefore performed in an inert atmosphere, in particular in an atmosphere of an inert gas, like nitrogen.

In some embodiments, in particular in embodiments in which the binder composition includes phenolics, in particular tannins oxidizing agents can be added. Oxidising agents as additives can serve to increase the oxidising rate of the phenolics in particular tannins. One example is the enzyme tyrosinase which oxidizes phenols to hydroxy-phenols/quinones and therefore accelerates the binder forming reaction.

In another embodiment, the oxidising agent is oxygen, which is supplied to the binder composition.

In one embodiment, the curing is performed in oxygen-enriched surroundings.

Binder Composition

The uncured binder composition comprises at least one hydrocolloid, and preferably at least one fatty acid ester of glycerol.

An advantage of using this binder composition is that is has a very simple composition which requires as little as only one component, namely at least one hydrocolloid. The binder composition preferably has two components, namely at least one hydrocolloid and at least one fatty acid ester of glycerol. The present invention therefore involves natural and non-toxic components and is therefore safe to work with. At the same time, the binder composition is based on renewable resources and has excellent properties concerning strength (both unaged and aged).

Because the binder composition used for the production of the coherent growth substrate products according to the present invention can be cured at ambient temperature or in the vicinity of ambient temperature, temperature-sensitive additives may be incorporated before curing of the binder composition.

In addition, the energy consumption during the production of the products is very low. The non-toxic and non-corrosive nature of embodiments of the binders in combination with the curing at ambient temperatures allows a much less complex machinery to be involved. At the same time, because of the curing at ambient temperature, the likelihood of uncured binder composition spots is strongly decreased.

Further important advantages are the self-repair capacities of growth substrate products produced from the binder compositions.

A further advantage of the growth substrate products is that they may be shaped as desired after application of the binder composition but prior to curing. This opens the possibility for making tailor-made products.

A further advantage is the strongly reduced punking risk.

Punking may be associated with exothermic reactions during manufacturing of the mineral wool product which increase temperatures through the thickness of the insulation causing a fusing or devitrification of the MMVF and eventually creating a fire hazard. In the worst case, punking causes fires in the stacked pallets stored in warehouses or during transportation.

Yet another advantage is the absence of emissions during curing, in particular the absence of VOC emissions.

Preferably, the binder is formaldehyde free. For the purpose of the present application, the term “formaldehyde free” is defined to characterize a mineral wool product where the emission is below 5 μg/m²/h of formaldehyde from the mineral wool product, preferably below 3 μg/m²/h. Preferably, the test is carried out in accordance with ISO 16000 for testing aldehyde emissions.

A surprising advantage of embodiments of coherent growth substrate products according to the present invention is that they show self-healing properties. After being exposed to very harsh conditions when MMVF products loose a part of their strength, the growth substrate product according to the present invention can regain a part of, the whole of or even exceed the original strength. In one embodiment, the aged strength is at least 80%, such as at least 90%, such as at least 100%, such as at least 130%, such as at least 150% of the unaged strength. This is in contrast to conventional growth substrate products for which the loss of strength after being exposed to harsh environmental conditions is irreversible.

While not wanting to be bound to any particular theory, the present inventors believe that this surprising property in coherent growth substrate products according to the present invention is due to the complex nature of the bonds formed in the network of the cured binder composition, such as the protein crosslinked by the phenol and/or quinone containing compound or crosslinked by an enzyme, which also includes quaternary structures and hydrogen bonds and allows bonds in the network to be established after returning to normal environmental conditions.

Hydrocolloid

Hydrocolloids are hydrophilic polymers, of vegetable, animal, microbial or synthetic origin, that generally contain many hydroxyl groups and may be polyelectrolytes. They are widely used to control the functional properties of aqueous foodstuffs.

Hydrocolloids may be proteins or polysaccharides and are fully or partially soluble in water and are used principally to increase the viscosity of the continuous phase (aqueous phase) i.e. as gelling agent or thickener. They can also be used as emulsifiers since their stabilizing effect on emulsions derives from an increase in viscosity of the aqueous phase.

A hydrocolloid usually consists of mixtures of similar, but not identical molecules and arising from different sources and methods of preparation. The thermal processing and for example, salt content, pH and temperature all affect the physical properties they exhibit. Descriptions of hydrocolloids often present idealised structures but since they are natural products (or derivatives) with structures determined by for example stochastic enzymatic action, not laid down exactly by the genetic code, the structure may vary from the idealised structure.

Many hydrocolloids are polyelectrolytes (for example alginate, gelatin, carboxymethylcellulose and xanthan gum).

Polyelectrolytes are polymers where a significant number of the repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged. Polyelectrolyte properties are thus similar to both electrolytes (salts) and polymers (high molecular weight compounds) and are sometimes called polysalts.

The charged groups ensure strong hydration, particularly on a per-molecule basis. The presence of counter-ions and co-ions (ions with the same charge as the polyelectrolyte) introduce complex behavior that is ion-specific.

A proportion of the counter-ions remain tightly associated with the polyelectrolyte, being trapped in its electrostatic field and so reducing their activity and mobility.

Preferably, the binder composition may comprise one or more counter-ion(s) selected from the group of Mg2+, Ca2+, Sr2+, Ba2+.

Another property of a polyelectrolyte is the high linear charge density (number of charged groups per unit length).

Generally neutral hydrocolloids are less soluble whereas polyelectrolytes are more soluble.

Many hydrocolloids also gel. Gels are liquid-water-containing networks showing solid-like behavior with characteristic strength, dependent on their concentration, and hardness and brittleness dependent on the structure of the hydrocolloid(s) present.

Hydrogels are hydrophilic crosslinked polymers that are capable of swelling to absorb and hold vast amounts of water. They are particularly known from their use in sanitary products. Commonly used materials make use of polyacrylates, but hydrogels may be made by crosslinking soluble hydrocolloids to make an insoluble but elastic and hydrophilic polymer.

Examples of hydrocolloids comprise: Agar agar, Alginate, Arabinoxylan, Carrageenan, Carboxymethylcellulose, Cellulose, Curdlan, Gelatin, Gellan, β-Glucan, Guar gum, Gum arabic, Locust bean gum, Pectin, Starch, Xanthan gum. In one embodiment, the at least one hydrocolloid is selected from the group consisting of gelatin, pectin, starch, alginate, agar agar, carrageenan, gellan gum, guar gum, gum arabic, locust bean gum, xanthan gum, cellulose derivatives such as carboxymethylcellulose, arabinoxylan, cellulose, curdlan, β-glucan.

Examples of polyelectrolytic hydrocolloids comprise: gelatin, pectin, alginate, carrageenan, gum arabic, xanthan gum, cellulose derivatives such as carboxymethylcellulose.

In one embodiment, the at least one hydrocolloid is a polyelectrolytic hydrocolloid.

The at least one hydrocolloid may be selected from the group consisting of gelatin, pectin, alginate, carrageenan, gum arabic, xanthan gum, cellulose derivatives such as carboxymethylcellulose.

The at least one hydrocolloid may be a gel former.

The at least one hydrocolloid may be used in the form of a salt, such as a salt of Na+, K+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+.

Gelatin

Gelatin is derived from chemical degradation of collagen. Gelatin may also be produced by recombinant techniques. Gelatin is water soluble and has a molecular weight of 10.000 to 500.000 g/mol, such as 30.000 to 300.000 g/mol dependent on the grade of hydrolysis. Gelatin is a widely used food product and it is therefore generally accepted that this compound is totally non-toxic and therefore no precautions are to be taken when handling gelatin.

Gelatin is a heterogeneous mixture of single or multi-stranded polypeptides, typically showing helix structures. Specifically, the triple helix of type I collagen extracted from skin and bones, as a source for gelatin, is composed of two al (I) and one α2(I) chains.

Gelatin solutions may undergo coil-helix transitions.

A-type gelatins are produced by acidic treatment. B-type gelatins are produced by basic treatment.

Chemical cross-links may be introduced to gelatin. In one embodiment, transglutaminase is used to link lysine to glutamine residues; in one embodiment, glutaraldehyde is used to link lysine to lysine, in one embodiment, tannins are used to link lysine residues.

The gelatin can also be further hydrolysed to smaller fragments of down to 3000 g/mol.

On cooling a gelatin solution, collagen like helices may be formed.

Other hydrocolloids may also comprise helix structures such as collagen like helices. Gelatin may form helix structures.

In one embodiment, the cured binder comprising hydrocolloid comprises helix structures.

In one embodiment, the at least one hydrocolloid is a low strength gelatin, such as a gelatin having a gel strength of 30 to 125 Bloom.

In one embodiment, the at least one hydrocolloid is a medium strength gelatin, such as a gelatin having a gel strength of 125 to 180 Bloom.

In one embodiment, the at least one hydrocolloid is a high strength gelatin, such as a gelatin having a gel strength of 180 to 300 Bloom.

In a preferred embodiment, the gelatin is preferably originating from one or more sources from the group consisting of mammal, bird species, such as from cow, pig, horse, fowl, and/or from scales, skin of fish.

In one embodiment, urea may be added to the binder composition. The inventors have found that the addition of even small amounts of urea causes denaturation of the gelatin, which can slow down the gelling, which might be desired in some embodiments. The addition of urea might also lead to a softening of the product.

The inventors have found that the carboxylic acid groups in gelatins interact strongly with trivalent and tetravalent ions, for example aluminum salts. This is especially true for type B gelatins which contain more carboxylic acid groups than type A gelatins.

The present inventors have found that in some embodiments, curing/drying of binder composition including gelatin should not start off at very high temperatures.

The inventors have found that starting the curing at low temperatures may lead to stronger products. Without being bound to any particular theory, it is assumed by the inventors that starting curing at high temperatures may lead to an impenetrable outer shell of the binder composition which hinders water from underneath to get out.

Surprisingly, the binder compositions including gelatins are very heat resistant. The present inventors have found that in some embodiments the cured binders can sustain temperatures up to 300° C. without degradation.

Pectin

Pectin is a heterogeneous grouping of acidic structural polysaccharides, found in fruit and vegetables which form acid-stable gels.

Generally, pectins do not possess exact structures, instead it may contain up to 17 different monosaccharides and over 20 types of different linkages. D-galacturonic acid residues form most of the molecules.

Gel strength increases with increasing Ca2+ concentration but reduces with temperature and acidity increase (pH<3).

Pectin may form helix structures.

The gelling ability of the di-cations is similar to that found with alginates (Mg2+ is much less than for Ca2+, Sr2+ being less than for Ba2+).

Alginate

Alginates are scaffolding polysaccharides produced by brown seaweeds.

Alginates are linear unbranched polymers containing β-(1,4)-linked D-mannuronic acid (M) and α-(1,4)-linked L-guluronic acid (G) residues. Alginate may also be a bacterial alginate, such as which are additionally O-acetylated. Alginates are not random copolymers but, according to the source algae, consist of blocks of similar and strictly alternating residues (that is, MMMMMM, GGGGGG and GMGMGMGM), each of which have different conformational preferences and behavior. Alginates may be prepared with a wide range of average molecular weights (50-100000 residues). The free carboxylic acids have a water molecule H3O+ firmly hydrogen bound to carboxylate. Ca2+ ions can replace this hydrogen bonding, zipping guluronate, but not mannuronate, chains together stoichiometrically in a so-called egg-box like conformation. Recombinant epimerases with different specificities may be used to produce designer alginates.

Alginate may form helix structures.

Carrageenan

Carrageenan is a collective term for scaffolding polysaccharides prepared by alkaline extraction (and modification) from red seaweed.

Carrageenans are linear polymers of about 25,000 galactose derivatives with regular but imprecise structures, dependent on the source and extraction conditions.

κ-carrageenan (kappa-carrageenan) is produced by alkaline elimination from μ-carrageenan isolated mostly from the tropical seaweed Kappaphycus alvarezii (also known as Eucheuma cottonii).

ι-carrageenan (iota-carrageenan) is produced by alkaline elimination from v-carrageenan isolated mostly from the Philippines seaweed Eucheuma denticulatum (also called Spinosum).

λ-carrageenan (lambda-carrageenan) (isolated mainly from Gigartina pistillata or Chondrus crispus) is converted into θ-carrageenan (theta-carrageenan) by alkaline elimination, but at a much slower rate than causes the production of ι-carrageenan and κ-carrageenan.

The strongest gels of κ-carrageenan are formed with K+ rather than Li+, Na+, Mg2+, Ca2+, or Sr2+.

All carrageenans may form helix structures.

Gum Arabic

Gum arabic is a complex and variable mixture of arabinogalactan oligosaccharides, polysaccharides and glycoproteins. Gum arabic consists of a mixture of lower relative molecular mass polysaccharide and higher molecular weight hydroxyproline-rich glycoprotein with a wide variability.

Gum arabic has a simultaneous presence of hydrophilic carbohydrate and hydrophobic protein.

Xanthan Gum

Xanthan gum is a microbial desiccation-resistant polymer prepared e.g. by aerobic submerged fermentation from Xanthomonas campestris.

Xanthan gum is an anionic polyelectrolyte with a β-(1,4)-D-glucopyranose glucan (as cellulose) backbone with side chains of -(3,1)-α-linked D-mannopyranose-(2,1)-β-D-glucuronic acid-(4,1)-β-D-mannopyranose on alternating residues.

Xanthan gums natural state has been proposed to be bimolecular antiparallel double helices. A conversion between the ordered double helical conformation and the single more-flexible extended chain may take place at between 40° C.-80° C. Xanthan gums may form helix structures.

Xanthan gums may contain cellulose.

Cellulose Derivatives

An example of a cellulose derivative is carboxymethylcellulose.

Carboxymethylcellulose (CMC) is a chemically modified derivative of cellulose formed by its reaction with alkali and chloroacetic acid.

The CMC structure is based on the β-(1,4)-D-glucopyranose polymer of cellulose. Different preparations may have different degrees of substitution, but it is generally in the range 0.6-0.95 derivatives per monomer unit.

Agar Agar

Agar agar is a scaffolding polysaccharide prepared from the same family of red seaweeds (Rhodophycae) as the carrageenans. It is commercially obtained from species of Gelidium and Gracilariae.

Agar agar consists of a mixture of agarose and agaropectin. Agarose is a linear polymer, of relative molecular mass (molecular weight) about 120,000, based on the -(1,3)-β-D-galactopyranose-(1,4)-3,6-anhydro-α-L-galactopyranose unit.

Agaropectin is a heterogeneous mixture of smaller molecules that occur in lesser amounts.

Agar agar may form helix structures.

Arabinoxylan

Arabinoxylans are naturally found in the bran of grasses (Graminiae).

Arabinoxylans consist of α-L-arabinofuranose residues attached as branch-points to β-(1,4)-linked D-xylopyranose polymeric backbone chains.

Arabinoxylan may form helix structures.

Cellulose

Cellulose is a scaffolding polysaccharide found in plants as microfibrils (2-20 nm diameter and 100-40 000 nm long). Cellulose is mostly prepared from wood pulp. Cellulose is also produced in a highly hydrated form by some bacteria (for example, Acetobacter xylinum).

Cellulose is a linear polymer of β-(1,4)-D-glucopyranose units in 4C1 conformation. There are four crystalline forms, la, 113, II and III.

Cellulose derivatives may be methyl cellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose.

Curdlan

Curdlan is a polymer prepared commercially from a mutant strain of Alcaligenes faecalis var. myxogenes. Curdlan (curdlan gum) is a moderate relative molecular mass, unbranched linear 1,3β-D glucan with no side-chains.

Curdlan may form helix structures.

Curdlan gum is insoluble in cold water but aqueous suspensions plasticize and briefly dissolve before producing reversible gels on heating to around 55° C. Heating at higher temperatures produces more resilient irreversible gels, which then remain on cooling.

Scleroglucan is also a 1,3β-D glucan but has additional 1,6β-links that confer solubility under ambient conditions.

Gellan

Gellan gum is a linear tetrasaccharide 4)-L-rhamnopyranosyl-(α-1,3)-D-glucopyranosyl-(β-1,4)-D-glucuronopyranosyl-(β-1,4)-D-glucopyranosyl-(β-1, with O(2) L-glyceryl and O(6) acetyl substituents on the 3-linked glucose.

Gellan may form helix structures.

β-Glucan

β-Glucans occur in the bran of grasses (Gramineae).

β-Glucans consist of linear unbranched polysaccharides of linked β-(1,3)- and β-(1,4)-D-glucopyranose units in a non-repeating but non-random order.

Guar Qum

Guar gum (also called guaran) is a reserve polysaccharide (seed flour) extracted from the seed of the leguminous shrub Cyamopsis tetragonoloba.

Guar gum is a galactomannana similar to locust bean gum consisting of a (1,4)-linked β-D-mannopyranose backbone with branch points from their 6-positions linked to α-D-galactose (that is, 1,6-linked-α-D-galactopyranose).

Guar gum is made up of non-ionic polydisperse rod-shaped polymer.

Unlike locust bean gum, it does not form gels.

Locust Bean Qum

Locust bean gum (also called Carob bean gum and Carubin) is a reserve polysaccharide (seed flour) extracted from the seed (kernels) of the carob tree (Ceratonia siliqua).

Locust bean gum is a galactomannana similar to guar gum consisting of a (1,4)-linked β-D-mannopyranose backbone with branch points from their 6-positions linked to α-D-galactose (that is, 1,6-linked α-D-galactopyranose).

Locust bean gum is polydisperse consisting of non-ionic molecules.

Starch

Starch consists of two types of molecules, amylose (normally 20-30%) and amylopectin (normally 70-80%). Both consist of polymers of α-D-glucose units in the 4C1 conformation. In amylose these are linked -(1,4)-, with the ring oxygen atoms all on the same side, whereas in amylopectin about one residue in every twenty or so is also linked -(1,6)-forming branch-points. The relative proportions of amylose to amylopectin and -(1,6)-branch-points both depend on the source of the starch. The starch may derive from the source of corn (maize), wheat, potato, tapioca and rice. Amylopectin (without amylose) can be isolated from ‘waxy’ maize starch whereas amylose (without amylopectin) is best isolated after specifically hydrolyzing the amylopectin with pullulanase.

Amylose may form helix structures.

In one embodiment, the at least one hydrocolloid is a functional derivative of starch such as cross-linked, oxidized, acetylated, hydroxypropylated and partially hydrolyzed starch.

In a preferred embodiment, the binder composition comprises at least two hydrocolloids, wherein one hydrocolloid is gelatin and the at least one other hydrocolloid is selected from the group consisting of pectin, starch, alginate, agar agar, carrageenan, gellan gum, guar gum, gum arabic, locust bean gum, xanthan gum, cellulose derivatives such as carboxymethylcellulose, arabinoxylan, cellulose, curdlan, β-glucan.

In one embodiment, the binder composition comprises at least two hydrocolloids, wherein one hydrocolloid is gelatin and the at least other hydrocolloid is pectin.

In one embodiment, the binder composition comprises at least two hydrocolloids, wherein one hydrocolloid is gelatin and the at least other hydrocolloid is alginate.

In one embodiment, the binder composition comprises at least two hydrocolloids, wherein one hydrocolloid is gelatin and the at least other hydrocolloid is carboxymethylcellulose.

In a preferred embodiment, the binder composition comprises at least two hydrocolloids, wherein one hydrocolloid is gelatin and wherein the gelatin is present in the aqueous binder composition in an amount of 10 to 95 wt.-%, such as 20 to 80 wt.-%, such as 30 to 70 wt.-%, such as 40 to 60 wt.-%, based on the weight of the hydrocolloids.

In one embodiment, the binder composition comprises at least two hydrocolloids, wherein the one hydrocolloid and the at least other hydrocolloid have complementary charges.

In one embodiment, the one hydrocolloid is one or more of gelatin or gum arabic having complementary charges from one or more hydrocolloid(s) selected from the group of pectin, alginate, carrageenan, xanthan gum or carboxymethylcellulose.

In one embodiment, the binder composition is capable of curing at a temperature of not more than 95° C., such as 5-95° C., such as 10-80° C., such as 20-60° C., such as 40-50° C.

In one embodiment, the aqueous binder composition is not a thermoset binder composition.

A thermosetting composition is in a soft solid or viscous liquid state, preferably comprising a prepolymer, preferably comprising a resin, that changes irreversibly into an infusible, insoluble polymer network by curing. Curing is typically induced by the action of heat, whereby typically temperatures above 95° C. are needed.

A cured thermosetting resin is called a thermoset or a thermosetting plastic/polymer—when used as the bulk material in a polymer composite, they are referred to as the thermoset polymer matrix. In one embodiment, the aqueous binder composition according to the present invention does not contain a poly(meth)acrylic acid, a salt of a poly(meth)acrylic acid or an ester of a poly(meth)acrylic acid.

In one embodiment, the at least one hydrocolloid is a biopolymer or modified biopolymer.

Biopolymers are polymers produced by living organisms. Biopolymers may contain monomeric units that are covalently bonded to form larger structures.

There are three main classes of biopolymers, classified according to the monomeric units used and the structure of the biopolymer formed: Polynucleotides (RNA and DNA), which are long polymers composed of 13 or more nucleotide monomers; Polypeptides, such as proteins, which are polymers of amino acids; Polysaccharides, such as linearly bonded polymeric carbohydrate structures.

Polysaccharides may be linear or branched; they are typically joined with glycosidic bonds. In addition, many saccharide units can undergo various chemical modifications, and may form parts of other molecules, such as glycoproteins.

In one embodiment, the at least one hydrocolloid is a biopolymer or modified biopolymer with a polydispersity index regarding molecular mass distribution of 1, such as 0.9 to 1.

In one embodiment, the binder composition comprises proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and the binder composition further comprises at least one phenol and/or quinone containing compound, such as tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups.

In one embodiment, the binder composition comprises proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and wherein the binder composition further comprises at least one enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide isomerase (EC 5.3.4.1), thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).

Fatty Acid Ester of Glycerol

The binder composition preferably comprises a component in form of at least one fatty acid ester of glycerol.

A fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated.

Glycerol is a polyol compound having the IUPAC name propane-1,2,3-triol.

Naturally occurring fats and oils are glycerol esters with fatty acids (also called triglycerides).

For the purpose of the present invention, the term fatty acid ester of glycerol refers to mono-, di-, and tri-esters of glycerol with fatty acids.

While the term fatty acid can in the context of the present invention be any carboxylic acid with an aliphatic chain, it is preferred that it is carboxylic acid with an aliphatic chain having 4 to 28 carbon atoms, preferably of an even number of carbon atoms. Preferably, the aliphatic chain of the fatty acid is unbranched.

In a preferred embodiment, the at least one fatty acid ester of glycerol is in form of a plant oil and/or animal oil. In the context of the present invention, the term “oil” comprises at least one fatty acid ester of glycerol in form of oils or fats.

In one preferred embodiment, the at least one fatty acid ester of glycerol is a plant-based oil.

In a preferred embodiment, the at least one fatty acid ester of glycerol is in form of fruit pulp fats such as palm oil, olive oil, avocado oil; seed-kernel fats such as lauric acid oils, such as coconut oil, palm kernel oil, babassu oil and other palm seed oils, other sources of lauric acid oils; palmitic-stearic acid oils such as cocoa butter, shea butter, borneo tallow and related fats (vegetable butters); palmitic acid oils such as cottonseed oil, kapok and related oils, pumpkin seed oil, corn (maize) oil, cereal oils; oleic-linoleic acid oils such as sunflower oil, sesame oil, linseed oil, perilla oil, hempseed oil, teaseed oil, safflower and niger seed oils, grape-seed oil, poppyseed oil, leguminous oil such as soybean oil, peanut oil, lupine oil; cruciferous oils such as rapeseed oil, mustard seed oil; conjugated acid oils such as tung oil and related oils, oiticica oil and related oils; substituted fatty acid oils such as castor oil, chaulmoogra, hydnocarpus and gorli oils, vernonia oil; animal fats such as land-animal fats such as lard, beef tallow, mutton tallow, horse fat, goose fat, chicken fat; marine oils such as whale oil and fish oil.

In a preferred embodiment, the at least one fatty acid ester of glycerol is in form of a plant oil, in particular selected from one or more components from the group consisting of linseed oil, olive oil, tung oil, coconut oil, hemp oil, rapeseed oil, and sunflower oil.

In a preferred embodiment, the at least one fatty acid ester of glycerol is selected from one or more components from the group consisting of a plant oil having an iodine number in the range of approximately 136 to 178, such as a linseed oil having an iodine number in the range of approximately 136 to 178, a plant oil having an iodine number in the range of approximately 80 to 88, such as an olive oil having an iodine number in the range of approximately 80 to 88, a plant oil having an iodine number in the range of approximately 163 to 173, such as tung oil having an iodine number in the range of approximately 163 to 173, a plant oil having an iodine number in the range of approximately 7 to 10, such as coconut oil having an iodine number in the range of approximately 7 to 10, a plant oil having an iodine number in the range of approximately 140 to 170, such as hemp oil having an iodine number in the range of approximately 140 to 170, a plant oil having an iodine number in the range of approximately 94 to 120, such as a rapeseed oil having an iodine number in the range of approximately 94 to 120, a plant oil having an iodine number in the range of approximately 118 to 144, such as a sunflower oil having an iodine number in the range of approximately 118 to 144.

In one embodiment, the at least one fatty acid ester of glycerol is not of natural origin.

In one embodiment, the at least one fatty acid ester of glycerol is a modified plant or animal oil.

In one embodiment, the at least one fatty acid ester of glycerol comprises at least one trans-fatty acid.

In an alternative preferred embodiment, the at least one fatty acid ester of glycerol is in form of an animal oil, such as a fish oil.

The present inventors have found that an important parameter for the fatty acid ester of glycerol used in the binder composition is the amount of unsaturation in the fatty acid. The amount of unsaturation in fatty acids is usually measured by the iodine number (also called iodine value or iodine absorption value or iodine index). The higher the iodine number, the more C═C bonds are present in the fatty acid. For the determination of the iodine number as a measure of the unsaturation of fatty acids, we make reference to Thomas, Alfred (2002) “Fats and fatty oils” in Ullmann's Encyclopedia of industrial chemistry, Weinheim, Wiley-VCH.

In a preferred embodiment, the at least one fatty acid ester of glycerol comprises a plant oil and/or animal oil having a iodine number of ≥75, such as 75 to 180, such as 130, such as 130 to 180.

In an alternative preferred embodiment, the at least one fatty acid ester of glycerol comprises a plant oil and/or animal oil having a iodine number of 100, such as 25.

In one embodiment, the at least one fatty acid ester of glycerol is a drying oil. For a definition of a drying oil, see Poth, Ulrich (2012) “Drying oils and related products” in Ullmann's Encyclopedia of industrial chemistry, Weinheim, Wiley-VCH.

Accordingly, the present inventors have found that particularly good results are achieved when the iodine number is either in a fairly high range or, alternatively, in a fairly low range. While not wanting to be bound by any particular theory, the present inventors assume that the advantageous properties inflicted by the fatty acid esters of high iodine number on the one hand and low iodine number on the other hand are based on different mechanisms. The present inventors assume that the advantageous properties of glycerol esters of fatty acids having a high iodine number might be due to the participation of the C═C double-bonds found in high numbers in these fatty acids in a crosslinking reaction, while the glycerol esters of fatty acids having a low iodine number and lacking high amounts of C═C double-bonds might allow a stabilization of the cured binder by van der Waals interactions.

In a preferred embodiment, the content of the fatty acid ester of glycerol is 0.5 to 40, such as 1 to 30, such as 1.5 to 20, such as 3 to 10, such as 4 to 7.5 wt.-%, based on dry hydrocolloid basis.

In one embodiment, the binder composition comprises gelatin, and the binder composition further comprises a tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups, preferably tannic acid, and the binder composition further comprises at least one fatty acid ester of glycerol, such as at least one fatty acid ester of glycerol selected from one or more components from the group consisting of linseed oil, olive oil, tung oil, coconut oil, hemp oil, rapeseed oil, and sunflower oil.

In one embodiment, the binder composition comprises gelatin, and the binder composition further comprises at least one enzyme which is a transglutaminase (EC 2.3.2.13), and the binder composition further comprises at least one fatty acid ester of glycerol, such as at least one fatty acid ester of glycerol selected from one or more components from the group consisting of linseed oil, olive oil, tung oil, coconut oil, hemp oil, rapeseed oil, and sunflower oil.

In one embodiment, the aqueous binder composition is formaldehyde-free.

In one embodiment, the binder composition is consisting essentially of:

-   -   at least one hydrocolloid;     -   optionally at least one fatty acid ester of glycerol;     -   optionally at least one pH-adjuster;     -   optionally at least one crosslinker;     -   optionally at least one anti-swelling agent;     -   optionally at least one anti-fouling agent     -   water.

In one embodiment, an oil may be added to the binder composition.

In one embodiment, the at least one oil is a non-emulsified hydrocarbon oil.

In one embodiment, the at least one oil is an emulsified hydrocarbon oil.

In one embodiment, the at least one oil is a plant-based oil.

In one embodiment, the at least one crosslinker is tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups.

In one embodiment, the at least one crosslinker is an enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide isomerase (EC 5.3.4.1), thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).

In one embodiment, the loss on ignition (LOI) of coherent growth substrate product is within the range of 0.1 to 25.0%, such as 0.3 to 18.0%, such as 0.5 to 12.0%, such as 0.7 to 8.0% by weight.

In one embodiment, the binder is not crosslinked. In an alternative embodiment, the binder is crosslinked.

In one embodiment, the at least one hydrocolloid is selected from the group consisting of gelatin, pectin, starch, alginate, agar agar, carrageenan, gellan gum, guar gum, gum arabic, locust bean gum, xanthan gum, cellulose derivatives such as carboxymethylcellulose, arabinoxylan, cellulose, curdlan, β-glucan.

In one embodiment, the at least one hydrocolloid is a polyelectrolytic hydrocolloid.

In one embodiment, the binder results from the curing of a binder composition in which the at least one hydrocolloid is selected from the group consisting of gelatin, pectin, alginate, carrageenan, gum arabic, xanthan gum, cellulose derivatives such as carboxymethylcellulose.

In one embodiment, the binder results from the curing of a binder composition comprising at least two hydrocolloids, wherein one hydrocolloid is gelatin and the at least one other hydrocolloid is selected from the group consisting of pectin, starch, alginate, agar agar, carrageenan, gellan gum, guar gum, gum arabic, locust bean gum, xanthan gum, cellulose derivatives such as carboxymethylcellulose, arabinoxylan, cellulose, curdlan, β-glucan. In one embodiment, the binder results from the curing of a binder composition in which the gelatin is present in an amount of 10 to 95 wt.-%, such as 20 to 80 wt.-%, such as 30 to 70 wt.-%, such as 40 to 60 wt.-%, based on the weight of the hydrocolloids.

In one embodiment, the binder results from the curing of a binder composition in which the one hydrocolloid and the at least other hydrocolloid have complementary charges.

In one embodiment, the loss on ignition (LOI) is within the range of 0.1 to 25.0%, such as 0.3 to 18.0%, such as 0.5 to 12.0%, such as 0.7 to 8.0% by weight.

In one embodiment, the binder results from the curing of a binder composition at a temperature of less than 95° C., such as 5-95° C., such as 10-80° C., such as 20-60° C., such as 40-50° C.

In one embodiment, the binder results from the curing of a binder composition which is not a thermoset binder composition.

In one embodiment, the binder results from a binder composition which does not contain a poly(meth)acrylic acid, a salt of a poly(meth)acrylic acid or an ester of a poly(meth)acrylic acid.

In one embodiment, the binder results from the curing of a binder composition comprising at least one hydrocolloid which is a biopolymer or modified biopolymer.

In one embodiment, the binder results from the curing of a binder composition comprising proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and the binder composition further comprises at least one phenol and/or quinone containing compound, such as tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups.

In one embodiment, the binder results from the curing of a binder composition comprising proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and wherein the binder composition further comprises at least one enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide isomerase (EC 5.3.4.1), thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).

Reaction of the Binder Composition Components

The present inventors have found that it is beneficial for the binder composition to be applied to the mineral fibres under acidic conditions. Therefore, in a preferred embodiment, the binder composition applied to the MMVF comprises a pH-adjuster, in particular in form of a pH buffer.

In a preferred embodiment, the binder composition in its uncured state has a pH value of less than 8, such as less than 7, such as less than 6.

The present inventors have found that in some embodiments, the curing of the binder composition is strongly accelerated under alkaline conditions. Therefore, in one embodiment, the binder composition for mineral fibres comprises a pH-adjuster, preferably in form of a base, such as organic base, such as amine or salts thereof, inorganic bases, such as metal hydroxide, such as KOH or NaOH, ammonia or salts thereof.

In a particular preferred embodiment, the pH adjuster is an alkaline metal hydroxide, in particular NaOH.

In a preferred embodiment, the binder composition according to the present invention has a pH of 7 to 10, such as 7.5 to 9.5, such as 8 to 9.

In one embodiment, an oil may be added to the binder composition.

In one embodiment, the at least one oil is a non-emulsified hydrocarbon oil.

In one embodiment, the at least one oil is an emulsified hydrocarbon oil.

In one embodiment, the at least one oil is a plant-based oil.

In one embodiment, the at least one crosslinker is tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups.

In one embodiment, the at least one crosslinker is an enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide isomerase (EC 5.3.4.1), thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).

Further additives may be additives containing calcium ions and antioxidants.

In one embodiment, the binder composition contains additives in form of linkers containing acyl groups and/or amine groups and/or thiol groups. These linkers can strengthen and/or modify the network of the cured binder.

In one embodiment, the binder compositions contain further additives in form of additives selected from the group consisting of PEG-type reagents, silanes, and hydroxylapatites.

Superabsorbent Polymer

Superabsorbent polymers, or SAPs, are hydrophilic materials which can absorb fluid and retain it under pressure without dissolution in the fluid being absorbed. The materials used are well-known. They are generally all synthesized by one of two routes. In the first, a water soluble polymer is cross-linked so that it can swell between cross-links but not dissolve. In the second, a water-soluble monomer is co-polymerized with a water insoluble monomer into blocks.

The earliest superabsorbent materials were saponified starch graft polyacrylonitrile copolymers. Synthetic superabsorbers include polyacrylic acid, polymaleic anhydride-vinyl monomer superabsorbents, starch-polyacrylic acid grafts, polyacrylonitrile-based polymers, cross-linked polyacrylamide, cross-linked sulfonated polystyrene, cross-linked n-vinyl pyrrolidone or vinyl pyrrolidone-acrylamide copolymer, and polyvinyl alcohol superabsorbents. These polymers absorb many times their own weight in aqueous fluid. Additional superabsorbent polymers include sodium propionate-acrylamide, poly(vinyl pyridine), poly(ethylene imine), polyphosphates, poly(ethylene oxide), vinyl alcohol copolymer with acrylamide, and vinyl alcohol copolymer with acrylic acid acrylate. These superabsorbent polymers can be used in this invention.

Superabsorbent polymers are beneficially used in plant growth substrates to improve water retention. The particles of superabsorbent polymer that are present in the growth substrate retain water, and then make the water available to the seed/seedling/plant when required. The superabsorbent polymer is also beneficial for water distribution, as it can be distributed throughout the growth substrate, and hence improves water distribution. By varying the amount of superabsorbent polymer in the substrate it is possible to set the maximum water content in the substrate. The rest of the water will drain from the growth substrate in use. The presence of the superabsorbent polymer will result in stability of the water content in the growth substrate product in use.

Superabsorbent polymers typically starts to degrade, decompose or be destroyed when exposed to temperatures of 50° C. or more, such as 100° C. or more or 200° C., such as between 50 to 300° C., such as 80° C. to 230° C. or 100° C. to 200° C. A significant benefit of the present invention is that, due to the use of a binder composition which cures at low temperatures, superabsorbent polymers may be added to the MMVF growth substrate before curing occurs. If the binder composition cured at 150° C. or more (as is typical for binder compositions in the prior art), then the superabsorbent polymer would have to be added after curing

A problem associated with adding superabsorbent polymers, or indeed any additive, after curing has occurred is that, typically, this step is carried out by users of the product rather than manufacturers. Once the binder composition has cured, the coherent growth substrate has formed. It is undesirable for additives to be added to the coherent growth substrate after manufacture, as this can lead to dusting problems. Specifically, particulates of additives become detached from the product during handling and transport. To avoid this, the growers, who use the coherent substrates in their growing facilities, typically add the superabsorbent polymer to the substrates. This can lead to overdosing or underdosing of the substrate. Further, adding additives after manufacture of the growth substrate can result in inhomogeneous distribution of additives throughout the growth substrate. An advantage of the present invention is that a coherent product can be formed which has the correct amount of superabsorbent polymer present, in the correct place. This is because the superabsorbent polymer is added before the coherent growth product is formed i.e. before curing of the binder composition. Therefore, the growers are not required to add the superabsorbent polymer themselves, and the problems of overdosing or underdosing are removed. Furthermore, the superabsorbent polymer does not become detached during handling and transport.

Another benefit associated with adding the superabsorbent polymer before the binder composition is cured, is that this allows the polymer to be contained more securely in the substrate. As the binder composition cures, this helps bind the superabsorbent polymer particles to the MMVF.

Preferably the superabsorbent polymer is one which starts to degrade, decompose or be destroyed at temperatures of less than or equal to 250° C., more preferably at 80° C. to 230° C., most preferably 100° C. to 200° C.

The superabsorbent polymer may be provided in dry form, hydrated form or partially hydrated form. When the SAP is in dry form it is usually provided in the form of particles or granules, which are generally flowable when dry. “Hydrated form” means that the superabsorbent polymer has absorbed at least 90% of the maximum amount of water it is capable of holding. “Partially hydrated form” means that the superabsorbent polymer has absorbed some water, but is able to absorb more water. “Dry form” means that the SAP comprises less than 5 wt % water, preferably less than 3 wt % water, preferably less than 1 wt % water, preferably no water.

The superabsorbent polymer can be added to the growth substrate as discussed above, in any form. Preferably, the superabsorbent polymer is in dry form when added, most preferably in particles. This is beneficial because solid particles of SAP are easier to handle than hydrated SAP, therefore, manufacturing is simplified. In addition, if SAPs are added in hydrated form, there is a possibility that dehydration may occur, which is deform the superabsorbent polymer.

The superabsorbent polymer is preferably added in amount of 0.1 wt % to 10 wt % based on the weight the growth substrate, preferably 0.5 wt % to 7 wt %, preferably 1 wt % to 5 wt %. The preferred amounts of superabsorbent polymer provide a desirable water buffer in the growth substrate product when it is used to propagated seeds or grow plants. This is particularly advantageous when the growth substrate product is in contact with soil as the superabsorbent polymer forms a reservoir of water within the growth substrate which is not drawn out be the suction pressure into the soil. Maintaining the water buffer helps to prevent plant necrosis and helps the plant survive until it is rooted-in in soil.

Preferably the superabsorbent polymer is added as particles. Preferably the weight average diameter of the particles of superabsorbent polymer is in the range of 0.05 mm to 2 mm, preferably 0.1 mm to 1 mm. An advantage of adding the superabsorbent polymer in the form of particles is that it simplifies the manufacturing process.

The superabsorbent polymer may be distributed evenly throughout the growth substrate product. This has the advantage of improving water distribution over the entire growth substrate. The superabsorbent polymer allows water to be retained across the substrate, thereby counteracting the effect of gravity i.e. for water to accumulate in the bottom of the substrate.

Alternatively, the superabsorbent polymer may be more concentrated in certain regions of the growth substrate. In one embodiment, the superabsorbent polymer is present in higher concentration around the region in which the seed/seedling/plant will be positioned, in comparison to the rest of the growth substrate, in order to provide optimal water levels.

Other Additives

Preferably further additives are added to the MMVF growth substrate. These additives may be added at the same time as the superabsorbent polymer and/or the uncured binder composition, as discussed above. Preferably the additives are added to the MMVF fibres as they form, along with the uncured binder composition and the superabsorbent polymer. This ensures the manufacturing procedure is simplified.

Preferably the additive is selected from clay, fertilisers, pesticides, micro-organisms, fungi, biologically active additives, pigments and mixtures thereof.

Preferably the fertiliser is a controlled-release fertiliser. This ensures that nutrients are released at the optimal time during the growth cycle. The fertilisers may be in the form of solid particles or a dispersion. Preferably it is in the form of solid particles. This is preferred as solids are easier to handle during manufacture than liquids.

The pigment may be in the form of solid particles or dispersion. Preferably it is in the form of solid particles. This is preferred as solids are easier to handle during manufacture than liquids. The pigment is used to colour the growth substrate product. For example, it may be desirable for the colour of the substrate to be darker, so that more light is absorbed. Equally, it may be preferable for the substrate to be lighter, in order to reflect light. In addition, it is possible to include a dark colour in the growth substrate as it makes it easier for the grower to check the position of any light coloured seeds in the mineral wool growth substrate. Additionally, a brown coloured mineral wool growth substrate is desirable for the end users as it has a closer resemblance to soil than light coloured mineral wool growth substrates.

The growth substrate may further comprise a wetting agent.

Growth Substrate

The present invention provides a coherent growth substrate product comprising; man-made vitreous fibres (MMVF) bonded with a cured binder composition; and a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid and preferably at least one fatty acid ester of glycerol.

Preferably the cured growth substrate of the present invention is a dry product prior to use to propagate seeds or grow plants. “Dry” means that the substrate comprises less than 5 wt % water, preferably less than 3 wt % water, preferably less than 1 wt % water, preferably less than 0.1 wt %, most preferably no water.

Preferably the growth substrate product comprises at least 90 wt % man-made vitreous fibres by weight of the total solids content of the growth substrate. An advantage of having such an amount of fibres present in the growth substrate product is that there are sufficient pores formed between the fibres to allow the growth substrate product to hold water and nutrients for the plant, whilst maintaining the ability for roots of the plants to permeate the growth substrate product. The remaining solid content is made up primarily of binder and additives.

Preferably the growth substrate product has an average density of from 30 to 150 kg/m³, such as 30 to 100 kg/m³, more preferably 40 to 90 kg/m³.

The growth substrate product preferably has a volume in the range 3 to 86,400 cm³, such as 5 to 30,000 cm³, preferably 8 to 20,000 cm³. The growth substrate product may be in the form of a product conventionally known as a plug, or in the form of a product conventionally known as a block, or in the form of a product conventionally known as a slab.

The growth substrate product may have dimensions conventional for the product type commonly known as a plug. Thus it may have height from 20 to 35 mm, often 25 to 28 mm, and length and width in the range 15 to 25 mm, often around 20 mm. In this case the substrate is often substantially cylindrical with the end surfaces of the cylinder forming the top and bottom surfaces of the growth substrate.

The volume of the growth substrate product in the form of a plug is preferably not more than 150 cm³. In general the volume of the growth substrate product in the form of a plug is in the range 0.6 to 40 cm³, preferably 3 to 150 cm³ and preferably not more than 100 cm³, more preferably not more than 80 cm³, in particular not more than 75 cm³, most preferably not more than 70 cm³. The minimum distance between the top and bottom surfaces of a plug is preferably less than 60 mm, more preferably less than 50 mm and in particular less than 40 mm or less.

Another embodiment of a plug has height from 30 to 50 mm, often around 40 mm and length and width in the range 20 to 40 mm, often around 30 mm. The growth substrate in this case is often of cuboid form. In this first case the volume of the growth substrate is often not more than 50 cm³, preferably not more than 40 cm³.

Alternatively the growth substrate may be of the type of plug described as the first coherent MMVF growth substrate in our publication WO2010/003677. In this case the volume of the growth substrate product is most preferably in the range to 10 to 40 cm³.

Preferably the growth substrate product in the form of a plug comprises a liquid-impermeable plastic covering surrounding its side surfaces only i.e. the bottom and top surfaces are not covered.

The growth substrate product may have dimensions conventional for the product type commonly known as a block. Thus it may have height from 5 to 20 cm, often 6 to 15 cm, and length and width in the range 4 to 30 cm, often 10 to 20 cm. In this case the substrate is often substantially cuboidal. The volume of the growth substrate product in the form of a block is preferably in the range 80 to 8000 cm³, preferably 50 cm³ to 5000 cm³, more preferably 100 cm³ to 350 cm³, most preferably 250 cm³ to 2500 cm³.

Preferably the growth substrate product in the form of a block comprises a liquid-impermeable covering surrounding its side surfaces only i.e. the bottom and top surfaces are not covered.

The growth substrate product may have dimensions conventional for the product type commonly known as a slab. Thus it may have height from 5 to 15 cm, often 7.5 to 12.5 cm, a width in the range of 5 to 30 cm, often 12 to 24 cm, and a length in the range 30 to 240 cm, often 40 to 200 cm. In this case the substrate is often substantially cuboidal. The volume of the growth substrate product in the form of a slab is preferably in the range 750 to 86,400 cm³, preferably 3 litres to 20 litres, more preferably 4 litres to 15 litres, most preferably 6 litres to 15 litres.

Preferably the growth substrate product in the form of a slab comprises a liquid impermeable covering encasing the slab, wherein a drain hole is formed by a first aperture in said covering. In addition, blocks contact the slab through a second opening in said covering. There may be further aperture in the covering to allow blocks to contact the slab i.e. one block may positioned on one aperture. The liquid impermeable covering has the effect of guiding liquid through the slab towards the drain hole, and moreover limits evaporation of fluids from the slab to the atmosphere.

The height is the vertical height of the growth substrate product when positioned as intended to be used and is thus the distance between the top surface and the bottom surface. The top surface is the surface that faces upwardly when the product is positioned as intended to be used and the bottom surface is the surface that faces downwardly (and on which the product rests) when the product is positioned as intended to be used.

In general, the growth substrate product may be of any appropriate shape including cylindrical, cuboidal and cubic. Usually the top and bottom surfaces are substantially planar.

The growth substrate product is in the form of a coherent mass. That is, the growth substrate is generally a coherent matrix of man-made vitreous fibres, which has been produced as such.

In the present invention, the term “height” means the distance from the bottom surface to the top surface when the substrate is in use. The term “length” means the longest distance between two sides i.e. the distance from one end to the other end when the substrate is in use. The term “width” is the distance between two sides, perpendicular to the length. These terms have their normal meaning in the art.

Use of the Growth Substrate Product

The present invention provides the use of a coherent growth substrate product as a substrate for growing plants or for propagating seeds;

wherein the coherent growth substrate product comprises;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition; and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid and preferably at least one fatty acid ester of glycerol.

The binder composition may have any of the preferred features described herein. The superabsorbent polymer may have any of the preferred features described herein. The coherent growth substrate product may have any of the preferred features described herein.

Method of Growing Plants

The present invention provides method of growing plants in a coherent growth substrate product, the method comprising:

-   -   (i) providing at least one growth substrate product;     -   (ii) positioning one or more plants for growth in the growth         substrate product; and     -   (iii) irrigating the growth substrate product;

wherein the coherent growth substrate product comprises;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition; and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid and preferably at least one fatty acid ester of glycerol.

Irrigation may occur by direct irrigation of the growth substrate product, that is, water is supplied directly to the growth substrate product, such as by a wetting line, tidal flooding, a dripper, sprinkler or other irrigation system.

The growth substrate product used in the method of growing plants is preferably as described above. The binder composition may have any of the preferred features described herein. The superabsorbent polymer may have any of the preferred features described herein.

Method of Propagating Seeds

The present invention provides a method of propagating seeds in a coherent growth substrate product, the method comprising:

-   -   (i) providing at least one growth substrate product     -   (ii) positioning one or more seeds in the growth substrate         product,     -   (iii) irrigating the growth substrate product; and     -   (iv) allowing germination and growth of the seed to form a         seedling;

wherein the coherent growth substrate product comprises;

-   -   man-made vitreous fibres (MMVF) bonded with a cured binder         composition; and     -   a superabsorbent polymer;

wherein the binder composition prior to curing comprises at least one hydrocolloid and preferably at least one fatty acid ester of glycerol.

Irrigation may occur by direct irrigation of the growth substrate product, that is, water is supplied directly to the growth substrate product, such as by a wetting line, tidal flooding, a dripper, sprinkler or other irrigation system.

The growth substrate product used in the method of propagating seeds is preferably as described above. The binder composition may have any of the preferred features described herein. The superabsorbent polymer may have any of the preferred features described herein.

Examples

In the following examples, several binder composition s which fall under the definition of the present invention were prepared and compared to binder compositions according to the prior art.

Test Methods for Binder Compositions According to the Prior Art

The following properties were determined for the binder compositions according the prior art.

Reagents

Silane (Momentive VS-142) was supplied by Momentive and was calculated as 100% for simplicity. All other components were supplied in high purity by Sigma-Aldrich and were assumed anhydrous for simplicity unless stated otherwise.

Binder Component Solids Content—Definition

The content of each of the components in a given binder solution before curing is based on the anhydrous mass of the components. The following formula can be used:

${{Binder}\mspace{14mu}{component}\mspace{14mu}{solids}\mspace{14mu}{content}\mspace{14mu}(\%)} = {\frac{\begin{matrix} {{{binder}\mspace{14mu}{component}\mspace{14mu} A\mspace{14mu}{solids}\mspace{14mu}(g)} +} \\ {{{binder}\mspace{14mu}{component}\mspace{14mu} B\mspace{14mu}{solids}\mspace{14mu}(g)} + \cdots} \end{matrix}}{{total}\mspace{14mu}{weight}\mspace{14mu}{of}\mspace{14mu}{mixture}\mspace{14mu}(g)} \times 100\%}$

Binder Solids—Definition and Procedure

The content of binder after curing is termed “binder solids”.

Disc-shaped stone wool samples (diameter: 5 cm; height 1 cm) were cut out of stone wool and heat-treated at 580° C. for at least 30 minutes to remove all organics. The solids of the binder mixture (see below for mixing examples) were measured by distributing a sample of the binder mixture (approx. 2 g) onto a heat treated stone wool disc in a tin foil container. The weight of the tin foil container containing the stone wool disc was weighed before and directly after addition of the binder mixture. Two such binder mixture loaded stone wool discs in tin foil containers were produced and they were then heated at 200° C. for 1 hour. After cooling and storing at room temperature for 10 minutes, the samples were weighed and the binder solids were calculated as an average of the two results. A binder with the desired binder solids could then be produced by diluting with the required amount of water and 10% aq. silane (Momentive VS-142).

Reaction Loss—Definition

The reaction loss is defined as the difference between the binder component solids content and the binder solids.

Mechanical Strength Studies (Bar Tests)—Procedure

The mechanical strength of the binders was tested in a bar test. For each binder, 16 bars were manufactured from a mixture of the binder and stone wool shots from the stone wool spinning production. The shots are particles which have the same melt composition as the stone wool fibers, and the shots are normally considered a waste product from the spinning process. The shots used for the bar composition have a size of 0.25-0.50 mm.

A 15% binder solids binder solution containing 0.5% silane (Momentive VS-142) of binder solids was obtained as described above under “binder solids”. A sample of this binder solution (16.0 g) was mixed well with shots (80.0 g). The resulting mixture was then filled into four slots in a heat resistant silicone form for making small bars (4×5 slots per form; slot top dimension: length=5.6 cm, width=2.5 cm; slot bottom dimension: length=5.3 cm, width=2.2 cm; slot height=1.1 cm). The mixtures placed in the slots were then pressed hard with a suitably sized flat metal bar to generate even bar surfaces. 16 bars from each binder were made in this fashion. The resulting bars were then cured at 200° C. for 1 h. After cooling to room temperature, the bars were carefully taken out of the containers. Five of the bars were aged in a water bath at 80° C. for 3 h or in an autoclave (15 min/120° C./1.2 bar).

After drying for 1-2 days, the aged bars as well as five unaged bars were broken in a 3 point bending test (test speed: 10.0 mm/min; rupture level: 50%; nominal strength: 30 N/mm²; support distance: 40 mm; max deflection 20 mm; nominal e-module 10000 N/mm²) on a Bent Tram machine to investigate their mechanical strengths. The bars were placed with the “top face” up (i.e. the face with the dimensions length=5.6 cm, width=2.5 cm) in the machine.

Loss of Ignition (LOI) of Bars

The loss of ignition (LOI) of bars was measured in small tin foil containers by treatment at 580° C. For each measurement, a tin foil container was first heat-treated at 580° C. for 15 minutes to remove all organics. The tin foil container was allowed to cool to ambient temperature, and was then weighed. Four bars (usually after being broken in the 3 point bending test) were placed into the tin foil container and the ensemble was weighed. The tin foil container containing bars was then heat-treated at 580° C. for 30 minutes, allowed to cool to ambient temperature, and finally weighed again. The LOI was then calculated using the following formula:

${{LOI}\mspace{14mu}(\%)} = {\frac{\begin{matrix} {{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{heat}\mspace{14mu}{treatment}\mspace{14mu}(g)} -} \\ {{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{after}\mspace{14mu}{heat}\mspace{14mu}{treatment}\mspace{14mu}(g)} \end{matrix}}{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{heat}\mspace{14mu}{treatment}\mspace{14mu}(g)} \times 100(\%)}$

Water Absorption Measurements

The water absorption of the binders was measured by weighing three bars and then submerging the bars in water (approx. 250 mL) in a beaker (565 mL, bottom Ø=9.5 cm; top Ø=10.5 cm; height=7.5 cm) for 3 h or 24 h. The bars were placed next to each other on the bottom of the beaker with the “top face” down (i.e. the face with the dimensions length=5.6 cm, width=2.5 cm). After the designated amount of time, the bars were lifted up one by one and allowed to drip off for one minute. The bars were held (gently) with the length side almost vertical so that the droplets would drip from a corner of the bar. The bars were then weighed and the water absorption was calculated using the following formula:

${{Waterabs}.(\%)} = {\frac{\begin{matrix} {{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{after}\mspace{14mu}{water}\mspace{14mu}{treatment}\mspace{14mu}(g)} -} \\ {{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{water}\mspace{14mu}{treatment}\mspace{14mu}(g)} \end{matrix}}{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{water}\mspace{14mu}{treatment}\mspace{14mu}(g)} \times 100(\%)}$

Reference Binder Compositions from the Prior Art

Binder Example, Reference Binder A (Phenol-Formaldehyde Resin Modified with Urea, a PUF-Resol)

A phenol-formaldehyde resin is prepared by reacting 37% aq. formaldehyde (606 g) and phenol (189 g) in the presence of 46% aq. potassium hydroxide (25.5 g) at a reaction temperature of 84° C. preceded by a heating rate of approximately 1° C. per minute. The reaction is continued at 84° C. until the acid tolerance of the resin is 4 and most of the phenol is converted. Urea (241 g) is then added and the mixture is cooled.

The acid tolerance (AT) expresses the number of times a given volume of a binder can be diluted with acid without the mixture becoming cloudy (the binder precipitates). Sulfuric acid is used to determine the stop criterion in a binder production and an acid tolerance lower than 4 indicates the end of the binder reaction. To measure the AT, a titrant is produced from diluting 2.5 mL conc. sulfuric acid (>99%) with 1 L ion exchanged water. 5 mL of the binder to be investigated is then titrated at room temperature with this titrant while keeping the binder in motion by manually shaking it; if preferred, use a magnetic stirrer and a magnetic stick. Titration is continued until a slight cloud appears in the binder, which does not disappear when the binder is shaken.

The acid tolerance (AT) is calculated by dividing the amount of acid used for the titration (mL) with the amount of sample (mL):

AT=(Used titration volume (mL))/(Sample volume (mL))

Using the urea-modified phenol-formaldehyde resin obtained, a binder is made by addition of 25% aq. ammonia (90 mL) and ammonium sulfate (13.2 g) followed by water (1.30 kg). The binder solids were then measured as described above and the mixture was diluted with the required amount of water and silane (Momentive VS-142) for mechanical strength studies (15% binder solids solution, 0.5% silane of binder solids).

Test Methods for Binder Compositions According to the Present Invention and Reference Binders

The following properties were determined for the binders according the present invention and reference binders.

Reagents

Speisegelatines, type A, porcine (120 bloom and 180 bloom) were obtained from Gelita AG. Tannorouge chestnut tree tannin was obtained from Brouwland bvba. TI Transglutaminase formula was obtained from Modernist Pantry. Coconut oil, hemp oil, olive oil, rapeseed oil and sunflower oil were obtained from Urtekram International A/S. Linseed oil was obtained from Borup Kemi I/S. Medium gel strength gelatin from porcine skin (170-195 g Bloom), sodium hydroxide, tung oil and all other components were obtained from Sigma-Aldrich. Unless stated otherwise, these components were assumed completely pure and anhydrous.

Binder Component Solids Content—Definition

The content of each of the components in a given binder solution before curing is based on the anhydrous mass of the components. The following formula can be used:

${{Binder}\mspace{14mu}{component}\mspace{14mu}{solids}\mspace{14mu}{content}\mspace{14mu}(\%)} = {\frac{\begin{matrix} {{{binder}\mspace{14mu}{component}\mspace{14mu} A\mspace{14mu}{solids}\mspace{14mu}(g)} +} \\ {{{binder}\mspace{14mu}{component}\mspace{14mu} B\mspace{14mu}{solids}\mspace{14mu}(g)} + \cdots} \end{matrix}}{{total}\mspace{14mu}{weight}\mspace{14mu}{of}\mspace{14mu}{mixture}\mspace{14mu}(g)} \times 100\%}$

Mechanical Strength Studies (Bar Tests)—Procedure

The mechanical strength of the binders was tested in a bar test. For each binder, 16-20 bars were manufactured from a mixture of the binder and stone wool shots from the stone wool spinning production. The shots are particles which have the same melt composition as the stone wool fibers, and the shots are normally considered a waste product from the spinning process. The shots used for the bar composition have a size of 0.25-0.50 mm.

A binder solution with approx. 15% binder component solids was obtained as described in the examples below. A sample of the binder solution (16.0 g) was mixed well with shots (80.0 g; pre-heated to 40° C. when used in combination with comparatively fast setting binders). The resulting mixture was then filled into four slots in a heat resistant silicone form for making small bars (4×5 slots per form; slot top dimension: length=5.6 cm, width=2.5 cm; slot bottom dimension: length=5.3 cm, width=2.2 cm; slot height=1.1 cm). During the manufacture of each bar, the mixtures placed in the slots were pressed as required and then evened out with a plastic spatula to generate an even bar surface. 16-20 bars from each binder were made in this fashion. The resulting bars were then cured at room temperature for 1-2 days. The bars were then carefully taken out of the containers, turned upside down and left for a day at room temperature to cure completely. Five of the bars were aged in a water bath at 80° C. for 3 h or in an autoclave (15 min/120° C./1.2 bar).

After drying for 1-2 days, the aged bars as well as five unaged bars were broken in a 3 point bending test (test speed: 10.0 mm/min; rupture level: 50%; nominal strength: 30 N/mm²; support distance: 40 mm; max deflection 20 mm; nominal e-module 10000 N/mm²) on a Bent Tram machine to investigate their mechanical strengths. The bars were placed with the “top face” up (i.e. the face with the dimensions length=5.6 cm, width=2.5 cm) in the machine.

Loss of Ignition (LOI) of Bars

The loss of ignition (LOI) of bars was measured in small tin foil containers by treatment at 580° C. For each measurement, a tin foil container was first heat-treated at 580° C. for 15 minutes to remove all organics. The tin foil container was allowed to cool to ambient temperature, and was then weighed. Four bars (usually after being broken in the 3 point bending test) were placed into the tin foil container and the ensemble was weighed. The tin foil container containing bars was then heat-treated at 580° C. for 30 minutes, allowed to cool to ambient temperature, and finally weighed again. The LOI was then calculated using the following formula:

${{LOI}\mspace{14mu}(\%)} = {\frac{\begin{matrix} {{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{heat}\mspace{14mu}{treatment}\mspace{14mu}(g)} -} \\ {{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{after}\mspace{14mu}{heat}\mspace{14mu}{treatment}\mspace{14mu}(g)} \end{matrix}}{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{heat}\mspace{14mu}{treatment}\mspace{14mu}(g)} \times 100(\%)}$

Water Absorption Measurements

The water absorption of the binders was measured by weighing three bars and then submerging the bars in water (approx. 250 mL) in a beaker (565 mL, bottom Ø=9.5 cm; top Ø=10.5 cm; height=7.5 cm) for 3 h or 24 h. The bars were placed next to each other on the bottom of the beaker with the “top face” down (i.e. the face with the dimensions length=5.6 cm, width=2.5 cm). After the designated amount of time, the bars were lifted up one by one and allowed to drip off for one minute. The bars were held (gently) with the length side almost vertical so that the droplets would drip from a corner of the bar. The bars were then weighed and the water absorption was calculated using the following formula:

${{Waterabs}.(\%)} = {\frac{\begin{matrix} {{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{after}\mspace{14mu}{water}\mspace{14mu}{treatment}\mspace{14mu}(g)} -} \\ {{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{water}\mspace{14mu}{treatment}\mspace{14mu}(g)} \end{matrix}}{{Weight}\mspace{14mu}{of}\mspace{14mu}{bars}\mspace{14mu}{before}\mspace{14mu}{water}\mspace{14mu}{treatment}\mspace{14mu}(g)} \times 100(\%)}$

Binder Compositions According to the Present Invention and Reference Binders

Binder Example, Entry B

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 12.0 g) in water (68.0 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.0). 1M NaOH (4.37 g) was then added (pH 9.1) followed by a portion of the above chestnut tree tannin solution (5.40 g; thus efficiently 1.20 g chestnut tree tannin). After stirring for 1-2 minutes further at 50° C., the resulting brown mixture (pH 9.1) was used in the subsequent experiments.

Binder Example, Entry 3

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.1). 1M NaOH (4.00 g) was added (pH 9.3) followed by a portion of the above chestnut tree tannin solution (4.50 g; thus efficiently 1.00 g chestnut tree tannin). Coconut oil (0.65 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting brown mixture (pH 9.3) was used in the subsequent experiments.

Binder Example, Entry 5

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 4.8). 1M NaOH (4.00 g) was added (pH 9.2) followed by a portion of the above chestnut tree tannin solution (4.50 g; thus efficiently 1.00 g chestnut tree tannin). Linseed oil (0.65 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting brown mixture (pH 9.2) was used in the subsequent experiments.

Binder Example, Entry 6

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 4.8). 1M NaOH (4.00 g) was added (pH 9.2) followed by a portion of the above chestnut tree tannin solution (4.50 g; thus efficiently 1.00 g chestnut tree tannin). Olive oil (0.65 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting brown mixture (pH 9.1) was used in the subsequent experiments.

Binder Example, Entry 9

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 4.8). 1M NaOH (4.00 g) was added (pH 9.3) followed by a portion of the above chestnut tree tannin solution (4.50 g; thus efficiently 1.00 g chestnut tree tannin). Tung oil (0.16 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting brown mixture (pH 9.4) was used in the subsequent experiments.

Binder Example, Entry 11

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.0). 1M NaOH (4.00 g) was added (pH 9.1) followed by a portion of the above chestnut tree tannin solution (4.50 g; thus efficiently 1.00 g chestnut tree tannin). Tung oil (1.13 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting brown mixture (pH 9.1) was used in the subsequent experiments.

Binder Example, Entry C

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 180 bloom, 12.0 g) in water (68.0 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.0). 1M NaOH (3.81 g) was then added (pH 9.1) followed by a portion of the above chestnut tree tannin solution (5.40 g; thus efficiently 1.20 g chestnut tree tannin). After stirring for 1-2 minutes further at 50° C., the resulting brown mixture (pH 9.3) was used in the subsequent experiments.

Binder Example, Entry 12

To 1M NaOH (15.75 g) stirred at room temperature was added chestnut tree tannin (4.50 g). Stirring was continued at room temperature for 5-10 min further, yielding a deep red-brown solution.

A mixture of gelatin (Speisegelatine, type A, porcine, 180 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.0). 1M NaOH (3.28 g) was added (pH 9.2) followed by a portion of the above chestnut tree tannin solution (4.50 g; thus efficiently 1.00 g chestnut tree tannin). Tung oil (0.65 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting brown mixture (pH 9.1) was used in the subsequent experiments.

Binder Example, Entry D

A mixture of gelatin (Porcine skin, medium gel strength, 12.0 g) in water (62.0 g) was stirred at 37° C. for approx. 15-30 min until a clear solution was obtained (pH 5.5). A solution of TI transglutaminase (0.60 g) in water (6.0 g) was then added. After stirring for 1-2 minutes further at 37° C., the resulting tan mixture (pH 5.5) was used in the subsequent experiments.

Binder Example, Entry 13

A mixture of gelatin (Porcine skin, medium gel strength, 12.0 g) in water (62.0 g) was stirred at 37° C. for approx. 15-30 min until a clear solution was obtained (pH 5.5). A solution of TI transglutaminase (0.60 g) in water (6.0 g) was added. Linseed oil (0.63 g) was then added under more vigorous stirring. After stirring more vigorously for approx. 1 minute at 37° C., the stirring speed was slowed down again and the resulting tan mixture (pH 5.5) was used in the subsequent experiments.

Binder Example, Entry E

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 12.0 g) in water (68.0 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 4.8). 1M NaOH (4.42 g) was then added. After stirring for 1-2 minutes further at 50° C., the resulting tan mixture (pH 9.0) was used in the subsequent experiments.

Binder Example, Entry 14

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.1). 1M NaOH (4.00 g) was added (pH 9.4). Tung oil (0.65 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting tan mixture (pH 9.1) was used in the subsequent experiments.

Binder Example, Entry 15

A mixture of gelatin (Speisegelatine, type A, porcine, 120 bloom, 10.0 g) in water (56.7 g) was stirred at 50° C. for approx. 15-30 min until a clear solution was obtained (pH 5.1). 1M NaOH (4.00 g) was added (pH 9.3). Tung oil (1.13 g) was then added under vigorous stirring. After stirring vigorously for approx. 1 minute at 50° C., the stirring speed was slowed down again and the resulting tan mixture (pH 9.1) was used in the subsequent experiments.

TABLE 1-1 Reference binder according to the prior art Example A Binder properties Binder solids (%) 15.0 Reaction loss (%) 28.5 pH 9.6 Bar curing conditions Temperature (° C./1 h) 200 Bar properties Mechanical strength, unaged (kN) 0.39 Mechanical strength, water bath aged (kN) 0.28 Mechanical strength, autoclave aged (kN) 0.28 LOI, unaged (%) 2.8 LOI, water bath aged (%) 2.8 Water absorption, 3 h (%) 4 Water absorption, 24 h (%) 8

TABLE 1-2 Hydrocolloid, crosslinker, mineral oil or fatty acid ester of glycerol Example B 1 2 3 4 5 6 Binder composition Hydrocolloid (%-wt.) Gelatin, Speisegelatine, 120 100 100 100 100 100 100 100 bloom Gelatin, Speisegelatine, 180 — — — — — — — bloom Crosslinker (%-wt.) ^([a]) Chestnut tree tannin 10 10 10 10 10 10 10 Fatty acid ester of glycerol (%-wt.) ^([a]) Mineral oil — 1.6 6.5 — — — — Coconut oil (iodine — — — 6.5 — — — number 7 to 10) Hemp oil (iodine — — — — 6.5 — — number 140 to 170) Linseed oil (iodine — — — — — 6.5 — number 136 to 178) Olive oil (iodine — — — — — — 6.5 number 80 to 88) Base (%-wt.) ^([b]) Sodium hydroxide 2.5 2.6 2.5 2.5 2.5 2.5 2.5 Binder mixing and bar manufacture Binder component solids 15.1 15.2 15.7 15.7 15.7 15.7 15.7 content (%) pH of binder mixture 9.1 9.1 9.1 9.3 9.1 9.2 9.1 Curing temperature (° C.) rt rt rt rt rt rt rt Bar properties Mechanical strength, 0.22 0.19 0.18 0.31 0.31 0.34 0.34 unaged (kN) Mechanical strength, 0.17 0.12 0.12 0.25 0.24 0.30 0.28 aged (kN) LOI, unaged (%) 2.9 2.9 2.9 3.0 3.0 3.0 3.0 LOI, water bath aged (%) 2.6 2.6 2.7 2.8 2.8 2.8 2.8 Water absorption, 3 h (%) 16 18 16 10 10 9 10 Water absorption, 24 h (%) 31 31 32 23 24 23 22 ^([a]) Of hydrocolloid. ^([b]) Of hydrocolloid + crosslinker.

TABLE 1-3 Hydrocolloid, crosslinker, fatty acid ester of glycerol Example B 7 8 9 10 11 C 12 Binder composition Hydrocolloid (%-wt.) Gelatin, Speisegelatine, 100 100 100 100 100 100 — — 120 bloom Gelatin, Speisegelatine, — — — — — — 100 100 180 bloom Crosslinker (%-wt.) ^([a]) Chestnut tree tannin 10 10 10 10 10 10 10 10 Fatty acid ester of glycerol (%-wt.) ^([a]) Rapeseed oil (iodine — 6.5 — — — — — — number 94 to 120) Sunflower oil (iodine — — 6.5 — — — — — number 118 to 144) Tung oil (iodine — — — 1.6 6.5 11.3 — 6.5 number 163 to 173) Base (%-wt.) ^([b]) Sodium hydroxide 2.5 2.5 2.5 2.6 2.5 2.4 2.3 2.2 Binder mixing and bar manufacture Binder component solids 15.1 15.7 15.7 15.2 15.7 16.3 15.1 15.9 content (%) pH of binder mixture 9.1 9.1 9.2 9.4 9.1 9.1 9.3 9.1 Curing temperature (° C.) rt rt rt rt rt rt rt rt Bar properties Mechanical strength, 0.22 0.28 0.26 0.29 0.32 0.28 0.24 0.37 unaged (kN) Mechanical strength, 0.17 0.25 0.21 0.22 0.22 0.21 0.17 0.34 aged (kN) LOI, unaged (%). 2.9 2.9 3.0 2.9 3.0 3.1 2.9 3.0 LOI, water bath aged (%) 2.6 2.8 2.8 2.7 2.9 3.0 2.8 2.9 Water absorption, 3 h (%) 16 11 10 11 8 8 13 9 Water absorption, 24 h (%) 31 25 24 24 23 20 25 22 ^([a]) Of hydrocolloid. ^([b]) Of hydrocolloid + crosslinker.

TABLE 1-4 Hydrocolloid, crosslinker, fatty acid ester of glycerol Example D 13 E 14 15 Binder composition Hydrocolloid (%-wt.) Gelatin (porcine skin), 100 100 — — — medium gel strength Gelatin, Speisegelatine, — — 100 100 100 120 bloom Crosslinker (%-wt.) ^([a]) TI transglutaminase 5 5 — — — Fatty acid ester of glycerol (%-wt.) ^([a]) Tung oil (iodine number — — — 6.5 11.3 163 to 173) Linseed oil (iodine — 5.3 — — — number 136 to 178) Base (%-wt.) ^([b]) Sodium hydroxide — — 1.4 1.5 1.5 Binder mixing and bar manufacture Binder component 15.6 16.3 14.4 15.1 15.7 solids content (%) pH of binder mixture 5.5 5.5 9.0 9.1 9.0 Curing temperature rt rt rt rt rt (° C.) Bar properties Mechanical strength, 0.28 0.29 0.16 0.22 0.19 unaged (kN) Mechanical strength, 0.20 0.20 — — — water bath aged (kN) Mechanical strength, — — 0.16 0.28 0.24 autoclave aged (kN) LOI, unaged (%) 3.0 3.2 2.7 3.0 3.1 LOI, water bath aged (%) 2.7 2.8 — — — Water absorption, 6 5 — — — 3 h (%) Water absorption, 9 10 — — — 24 h (%) ^([a]) Of hydrocolloid. ^([b]) Of hydrocolloid + crosslinker.

As can be seen from the above results, the binder composition used in the present invention cures at room temperature. This means that temperature-sensitive additives i.e. superabsorbent polymers may be added to the MMVF before curing occurs. 

1. A method of producing a coherent growth substrate product formed of man-made vitreous fibres (MMVF), comprising the steps of: I. providing MMVF; II. providing an uncured binder composition; III. providing a superabsorbent polymer; IV. forming a mixture of the MMVF, the uncured binder composition and the superabsorbent polymer; V. curing the uncured binder composition in the mixture to form the coherent growth substrate product; wherein the uncured binder composition comprises at least one hydrocolloid; and wherein the uncured binder composition comprises: proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and the binder composition further comprises at least one phenol and/or quinone containing compound such as tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups; and/or proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and wherein the binder composition further comprises at least one enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide isomerase (EC 5.3.4.1), thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).
 2. The method according to claim 1, wherein the uncured binder composition further comprises at least one fatty acid ester of glycerol.
 3. The method according to claim 2, wherein the uncured binder composition and the superabsorbent polymer are added simultaneously.
 4. The method according to claim 1, wherein the mixture in step (iv) is formed by adding the uncured binder composition and the superabsorbent polymer to the MMVF after the fibres are formed.
 5. The method according to claim 4, wherein the uncured binder composition and the superabsorbent polymer are added simultaneously.
 6. The method according to claim 1, wherein the superabsorbent polymer is a solid, preferably solid particles.
 7. The method according to claim 1, wherein of 0.1 wt % to 10 wt % of superabsorbent polymer, based on the weight the growth substrate is provided, preferably 0.5 wt % to 7 wt %, preferably 1 wt % to 5 wt %.
 8. The method according to claim 1, further comprising the step of providing an additive before the uncured binder composition is cured, wherein the additive is selected from clay, fertilisers, pesticides, micro-organisms, biologically active additives, pigments, wetting agents and mixtures thereof.
 9. (canceled)
 10. (canceled)
 11. (canceled)
 12. The method according to claim 1, wherein the uncured binder composition comprises at least two hydrocolloids, wherein one hydrocolloid is gelatin and the at least one other hydrocolloid is selected from the group consisting of pectin, starch, alginate, agar agar, carrageenan, gellan gum, guar gum, gum arabic, locust bean gum, xanthan gum, cellulose derivatives such as carboxymethylcellulose, arabinoxylan, cellulose, curdlan, β-glucan.
 13. The method according to claim 8, wherein the gelatin is present in the binder composition in an amount of 10 to 95 wt.-%, such as 20 to 80 wt.-%, such as 30 to 70 wt.-%, such as 40 to 60 wt.-%, based on the weight of the hydrocolloids.
 14. (canceled)
 15. The method according to claim 2, wherein the at least one fatty acid ester of glycerol is in form of a plant oil and/or animal oil.
 16. The method according to claim 2, wherein the at least one fatty acid ester of glycerol is a plant-based oil.
 17. The method according to claim 2, wherein the at least one fatty acid ester of glycerol is selected from one or more components from the group consisting of linseed oil, olive oil, tung oil, coconut oil, hemp oil, rapeseed oil, and sunflower oil.
 18. The method according to claim 2, wherein the at least one fatty acid ester of glycerol is in form of an animal oil, such as fish oil.
 19. The method according to claim 2, wherein the at least one fatty acid ester of glycerol comprises a plant oil and/or animal oil having a iodine number of such as 75 to 180, such as 130, such as 130 to
 180. 20. The method according to claim 2, wherein the at least one fatty acid ester of glycerol comprises a plant oil and/or animal oil having a iodine number of ≤100, such as ≤25.
 21. The method according to claim 2, wherein the content of the fatty acid ester of glycerol is 0.5 to 40, such as 1 to 30, such as 1.5 to 15, such as 3 to 10, such as 4 to 7.5 wt. %, based on dry hydrocolloid basis.
 22. The method according to claim 1, wherein the step (v) of curing occurs at a temperature of not more than 95° C., such as 5-95° C., such as 10-80° C., such as 20-60° C., such as 40-50° C.
 23. The method according to claim 1, wherein the binder composition is not a thermoset binder composition.
 24. (canceled)
 25. (canceled)
 26. The method according to claim 1, wherein the binder composition is formaldehyde-free.
 27. The method according to claim 1, wherein the binder composition consists essentially of: at least one hydrocolloid; at least one fatty acid ester of glycerol; optionally at least one pH-adjuster; optionally at least one crosslinker; optionally at least one anti-swelling agent optionally at least one anti-fouling agent; water.
 28. (canceled)
 29. (canceled)
 30. A coherent growth substrate product comprising; man-made vitreous fibres (MMVF) bonded with a cured binder composition; and a superabsorbent polymer; wherein the binder composition prior to curing comprises at least one hydrocolloid, and wherein the uncured binder composition comprises: proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and the binder composition further composes at least one phenol end/or quinone containing compound, such as tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups; and/or proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and wherein the binder composition further comprises at least one enzyme selected front the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide isomerase (EC 5.3.4.1), thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).
 31. The coherent growth substrate product according to claim 30, wherein the loss on ignition (LOI) is within the range of 0.1 to 25.0%, such as 0.3 to 18.0%, such as 0.5 to 12.0%, such as 0.7 to 8.0% by weight.
 32. (canceled)
 33. Use of a coherent growth substrate product as a substrate for growing plants or for propagating seeds; wherein the coherent growth substrate product comprises; man-made vitreous fibres (MMVF) bonded with a cured binder composition; and a superabsorbent polymer; wherein the binder composition prior to curing comprises at least one hydrocolloid, and wherein the binder composition comprises: proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and the binder composition further composes at least one phenol and/or quinone containing compound, such as tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cups; and/or proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and wherein the binder composition further comprises at least one enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13V protein disulfide isomerase (EC 5.3.4.1); thiol oxidase (EC 1.8.3.2), polyphenol oxidase (EC 1.14.18.1), in particular catechol oxidase, tyrosine oxidase, and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).
 34. (canceled)
 35. A method of growing plants or propagating seeds in a coherent growth substrate product, the method comprising: (i) providing at least one growth substrate product; (ii) positioning one or more plants or one or more seeds for growth in the growth substrate product; and (iii) irrigating the growth substrate product; wherein the coherent growth substrate product comprises; man-made vitreous fibres (MMVF) bonded with a cured binder composition; and a superabsorbent polymer; wherein the binder composition prior to curing comprises at least one hydrocolloid, and wherein the binder composition comprises: proteins from animal sources, inducting collagen, gelatin, and hydrolysed gelatin, and the binder composition further comprises at least one phenol and/or quinone containing compound, such as tannin selected from one or more components from the group consisting of tannic acid, condensed tannins (proanthocyanidins), hydrolysable tannins, gallotannins, ellagitannins, complex tannins, and/or tannin originating from one or more of oak, chestnut, staghorn sumac and fringe cuds; and/or proteins from animal sources, including collagen, gelatin, and hydrolysed gelatin, and wherein the binder composition further comprises at least one enzyme selected from the group consisting of transglutaminase (EC 2.3.2.13), protein disulfide 1.14.18.1), in particular catechol oxidase, tyrosine oxidase and phenoloxidase, lysyl oxidase (EC 1.4.3.13), and peroxidase (EC 1.11.1.7).
 36. (canceled)
 37. (canceled)
 38. (canceled) 